This invention relates to demand or impulse liquid jets of the type wherein a droplet of liquid is ejected from an orifice in response to a command at a frequency which can vary as the frequency of the commands.
Liquid jets of this type are employed in the ink jet art wherein droplets of ink are projected toward paper or another recording medium. In the ink jet art, it is particularly desirable to array a plurality of jets in a predetermined configuration so as to permit the simultaneous and selective ejection of droplets from a plurality of jets toward the paper or copy medium. Preferably, the jets are arrayed in a rather dense manner, i.e., the jets are closely packed with relatively small orifices, e.g., 5 mils in diameter, in order to achieve a high degree of resolution in the printing of alphanumeric material.
Copending application Ser. No. 336,603, filed Jan. 4, 1982 discloses a particular ink jet configuration adapted to be arrayed for use in alphanumeric printing. The technique for achieving an extremely dense array of the ink jets disclosed in the aforesaid application Ser. No. 336,603 are shown in copending application Ser. No. 229,992, filed Jan. 30, 1981. In the aforesaid application Ser. No. 229,992, the high density of the ink jet array is achieved by the use of untapered waveguides which couple displacement of a transducer to an ink chamber so as to expand and contract the chamber and eject a droplet of ink. It will be appreciated that the volume of ink in the chamber of this type is extremely small. The substantial or relatively large expansion and contraction of that volume must be achieved in order to eject a droplet of ink.